Method of producing abrasive paper and the like



m 18, 1933; c. MUNCH 1,918,418

' METHOD OF PRODUCING ABRASIVE PAPER AND THE LIKE Filed Sept. 9, 1931 Jnvan for:

1 AZLfornez s Patented July 18, 1933 cam. ufincn, or DUREN, GERMANYMETHOD OF PRODUCING ABBASIVE ZPAPER AND THE LIKE Application filedSeptember 9, 1931, Serial No. 561,883, and in Germany September 9, 1930.

lulose ester solution is applied alone on to the support, whereupon theabrasive is strewn on to-the applied layer whilst the same is stillsticky. Consequently, these known methods are inconvenient and waste 15time, and on the abrasivepaper produced thereby the abrasive grainsarenot uniformly distributed over the grinding surface and are notsufficiently embedded in the binding medium, so that the grindingsurface is also 20 not smooth. The grinding coating of the abrasivepaper thus produced is as a rule subsequently provided with a furtherlayer of cellulose ester, in order to smoothen the grinding surface. Bythis measure however the known processes of the kind in question arerendered still more complicated, without overcoming the objection of theirregular distribution of the grains of abrasive on the support. Theseinconveniences are overcome according to the invention. 7

The invention consists substantially in that first the cellulose ester,dissolved in a solvent, possessing a low boiling point, is mixed withthe abrasive, after which the mixture thus obtained is applied inthoroughly mixed condition continually on to the circumference of arotating cylinder and then continually brushed off from the periphery ofthe cylinder by means of a paper or fabric web moved in the samedirection and bearing against the circumference of the cylinder so thatthe mixture is transferred to the paper or fabric web. The new method ismuch more simple than the known methods of its kind and the abrasivepaper produced thereby shows a very uniform distribution of the abrasiveparticles on the support with proper embedding in the binding medium andconsequently a ver smooth surface produced without any furt er measures.

of the accompanying drawmg is preferably 60 employed, which consistssubstantially of three cylinders, a, b, 0, the two cylinders 12, 0 ofwhich are arranged, rotatable in clockwise direction, side by side sothat a gap F is left between them corresponding in width approximatelyto the thickness of the coating to be applied to the support, whereasthe third cylinder a is mounted rotatable in the same direction underthe cylinder b at a certain distance so that a passage is left the widthof which corresponds to the thickness of the support. The space abovethe gap F between the cylinder b and the cylinder 0 provided at the topwith a scraper. d, is filled with a mixture of cellulose ester solutionand granular abrasive, and at the same time the paper or fabric web 6designed to serve as support is conducted from below over the cylinder aand between this cylinder and the cylinder 6, and consequently conveyedby the so cylinders a, b in the direction indicated 'in the drawing bythe arrow. Owing to the rotating movement of the cylinders b and a acontinuous effective mixing of the mixture between these cylinders takesplace automatically, a portion of the mixture being continually. carriedalong by the periphery of the cylinder 1) in the form of a thin layer 9,the thickness of which corresponds approximately to the width of the gapF between the cylinders b and 0. As soon as the layer 9 of mixturecarried along by the periphery of the cylinder 1) arrives on the movedsuport e, it is scraped off from the cylinder 6 y this support andcontinually applied in a smooth layer onto the support 6, where itrapidly dries.

I claim In a method of producing abrasive paper and similar articlesprovided with a coating,

in combination, the steps of dissolvin celluing, and bringing amovingpaper web passlose ester in a solvent having a low oiling ing over athird cylinder in contact With the point, mixing the dissolved celluloseester first cylinder, all the three cylinders rotating with an abrasivematerial, continuously inin the same direction, the mixture carried by 5troducing the mixture into a space between the first cylinder beingtransferred to said 70 a first and a second cylinder, said spacecorrepaper web. sponding to the desired thickness of the coat- CARL MUNCH.

so I

